Polyethylene having an ultra-high molecular weight exceeding several hundred thousand has dramatically improved impact resistance, self-lubrication, wear resistance, weather resistance, chemical resistance, and dimensional stability, and exhibits high physical properties on a par with those of engineering plastics. Consequently, the application thereof in lining materials, line parts in the food industry, machine parts, prosthetic joints, sports equipment, fibers, filters in which porous sinter formed products are used, separators for secondary batteries such as lead-acid batteries and lithium ion batteries in which microporous membranes are used, and so forth has been attempted by various shaping methods.